I would read my replies above ^ on this topic = write down as a list. tick off every single checkpoint.

Fueling Parts & Carb OK & checked over? = then we are done with the carbs.

Then the electrics or plugs would be your enemy , I would go here below …
(GV125/Gt125 = same engine, same carb, same coils = same behavior)
(Follow my replies in those threads, as i go quite deep on electric dramas & HOW to test them yourself)

Yes,
Faulty Coils & Regulators happen to all hyosungs. They are just a cheaply made parts that die out eventually. The japanese win when it comes to electrics.
— > Could also explain your plugs not doing their job or otherwise fouled/annoyed

Remember this always:
High revs / RPM needle stuck high / very slow to drop revs down = Air Leaks (anything air flows thru) or CV sliders stuck or choke is not off (still on choke)